The main objective of this note is to describe a real-time fault diagnosis and control for a cylindroconical fermenter to laboratory scale as an alternative to the classic systems. Development of a good controller for a fed-batch reactor is not enough without a fault diagnosis system. We are working to expand this idea. The failure detection system is based on the parity space approach joined with a fuzzy controller with more robustness and of superior performance in MIMO systems compared to conventional strategies. A 2-week period is reported.